NC0004961_Revised Plan 5/8/15_20150527

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' MAY 2 7 2Di5
peon
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Riverbend Steam Station Ash Basin
1 Plan for Identification of New
Discharges
1 NPDES Permit NC0004961
Revised May 8, 2015
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DUKE
1 ENERGY
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Duke Energy Carolinas,LLC l Plan for Identification of New Discharges En
Riverbend Steam Station Ash Basin
' TABLE OF CONTENTS
Table of Contents
I Page
I Report Verification i
Table of Contents ii
List of Tables and Figures iii
ISection 1 - Introduction 1
Section 2 -Site Description 3
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2.1 Plant Description 3
2.2 Ash Basin Description 3
12.3 Permitted NPDES Wastewater and Stormwater Outfalls 3
Section 3- Site Geology and Hydrogeology 7
I 3.1 Site Geologic/Soil Framework 7
3.2 Site Hydrogeologic Framework 7
Section 4- Identification of New Discharges 9
I4.1 Purpose of Inspection 9
4.2 Seepage 9
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4.3 Area To Be Inspected for New Discharges 9
4.4 Inspection Procedure 9
I 4.5 Stormwater Outfalls 10
Section 5 - References 11
Appendices
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A—Riverbend Station Ash Basin— Inspection for Identification of New Discharges
B—Areas of Wetness
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Duke Energy Carolinas,LLC I Plan for Identification of New Discharges EN
Riverbend Steam Station Ash Basin J
ILIST OF TABLES AND FIGURES
1 List of Tables
1 Table 1 - NPDES Wastewater and Stormwater Outfalls
I List of Figures
IFigure 1 -Site Location Map
IFigure 2-Areas to be Inspected for Seeps
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Duke Energy Carolinas,LLC I Plan for Identification of New Discharges �1�Riverbend Steam Station Ash Basin
SECTION 1-INTRODUCTION
Section 1 - Introduction
The purpose of this document is to address the requirements of North Carolina General Statute
(GS)130A-309.210 (d) Identification and assessment of discharges;correction of unpermitted
1 discharges, as modified by North Carolina Senate Bill 729, for the Riverbend Steam Station
(RBSS) ash basin operated under National Pollutant Discharge Elimination System (NPDES)
Permit NC0004961.
The following requirements are contained in General Statute 130A-309.210:
d) identification of New Discharges. —No later than October 1, 2014, the
owner of a coal combustion residuals surface impoundment shall submit a
proposed Plan for the Identification of New Discharges to the Department for its
1 review and approval as provided in this subsection.
1) The proposed Plan for the Identification of New Discharges shall include,
at a minimum, all of the following:
a. A procedure for routine inspection of the coal combustion residuals
surface impoundment to identify indicators of potential new
discharges, including toe drain outfalls, seeps, and weeps.
b. A procedure for determining whether a new discharge is actually
present.
c. A procedure for notifying the Department when a new discharge is
confirmed.
d. Any other information related to the identification of new discharges
' required by the Department.
2) The Department shall approve the Plan for the Identification of New
Discharges if it determines that the Plan complies with the requirements
of this subsection and will be sufficient to protect public health, safety,
and welfare;the environment;and natural resources.
3) No later than 30 days from the approval of the Plan for the Identification
' of New Discharges, the owner shall begin implementation of the Plan in
accordance with the Plan.
The North Carolina Senate Bill 729 establishes the submittal date of this Plan for Identification
of New Discharges no later than October 1, 2014.
' This bill also modified GS 130A to establish the following submittals that are related to this Plan.
GS130A-309.210(a)was modified to require:
2) No later than December 31, 2014, the owner of a coal combustion
residuals surface impoundment shall submit a topographic map that
identifies the location of all (i) outfalls from engineered channels
designed or improved for the purpose of collecting water from the toe of
the impoundment and(ii) seeps and weeps discharging from the
impoundment that are not captured by engineered channels designed or
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Duke Energy Carolinas,LLC I Plan for Identification of New Discharges EN
Riverbend Steam Station Ash Basin J
1 SECTION 1 -INTRODUCTION
improved for the purpose of collecting water from the toe of the
I impoundment to the Department. The topographic map shall comply with
all of the following:
a. Be at a scale as required by the Department.
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b. Specify the latitude and longitude of each toe drain outfall, seep, and
weep.
c. Specify whether the discharge from each toe drain outfall, seep, and
weep is continuous or intermittent.
d. Provide an average flow measurement of the discharge from each toe
I drain outfall, seep, and weep including a description of the method
used to measure average flow.
e. Specify whether the discharge from each toe drain outfall, seep, and
I weep identified reaches the surface waters of the State. If the
discharge from a toe drain outfall, seep, or weep reaches the surface
waters of the State, the map shall specify the latitude and longitude of
I where the discharge reaches the surface waters of the State.
f. Include any other information related to the topographic map required
by the Department.
IThe inspection procedures presented in this plan, developed to satisfy the requirements of
GS130A-309.210 (d), will be used as the basis for developing the topographic map required by
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GS130A-309.210 (a)(2).
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dr' DUKE Environmental Services
leENERGY® Duke Energy
CAROLINAS 526 South Church Street
Charlotte, NC 28202
Mailing Address.
EC13K/P.O.Box 1006
Charlotte, NC 28201-1006
May 21, 2015
Mr. Jeffrey Poupart, Section Chief RECEIVED/DENR/DWR
NC Division of Water Resources
1617 Mail Service Center
Raleigh, NC 27699-1617 MAY 2 7 2015
water Quality
Subject: Revised Plan for Identification of New Discharges Permitting Section
Riverbend Steam Station
NC0004961
Gaston County
Dear: Mr. Poupart,
Duke Energy hereby formally submits the attached revised version of the Riverbend Plan for
Identification of New Discharges. This version includes edits in response to comments made by
the NC Division of Water Resources.
If you have any questions regarding this submittal, please contact me at [phone] or
richard.baker(c�duke-energv.com.
I certhr, under penalty of law, that this document and all attachments were prepared under my direction or
supervision in accordance with a system designed to assure that qualified personnel properly gather and
evaluate the information submitted. Based on my inquiry of the person or persons who manage the system, or
those persons directly responsible for gathering the information, the information submitted is, to the best of my
knowledge and belief true, accurate, and complete. 1 am aware that there are significant penalties for
submitting false information, including the possibility offines and imprisonment for knowing violations.
Sincerely,
civIt ql
Richard E. Baker, Jr., P.E., PMP
Director, Environmental Programs
Duke Energy EHS - CCP
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Duke Energy Carolinas,LLC I Plan for Identification of New Discharges EN
Riverbend Steam Station Ash Basin
1 SECTION 2-SITE DESCRIPTION
i Section 2 - Site Description
2.1 Plant Description
I RBSS is a former coal-fired electricity generating facility which had a capacity of 454 megawatts
located in Gaston County, North Carolina, near the town of Mt. Holly (Figure 1). As of April 1,
2013, all of the coal-fired units have been retired. The site is located between the south bank of
I the Catawba River on Mountain Island Lake and the north side of Horseshoe Bend Beach
Road. The surrounding area generally consists of residential properties, undeveloped land, and
Mountain Island Lake
1 2.2 Ash Basin Description
The ash basin system consists of a Primary Cell and a Secondary Cell, separated by an
Iintermediate dike. The ash basin at RBSS originally consisted of a single-cell basin
commissioned in 1957 and was expanded in 1979. The single basin was divided by
constructing a divider dike to form two separate cells in 1986.
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The ash basin is located approximately 2,400 feet to the northeast of the power plant, adjacent
to Mountain Island Lake, as shown on Figure 2. The Primary Cell is impounded by an earthen
I embankment dike located on the west side of the Primary Cell. The Secondary Cell is
impounded by an earthen embankment dike located along the northeast side of the Secondary
Cell.
IThe surface area of the Primary Cell is approximately 41 acres with an approximate maximum
pond elevation of 724 feet. The surface area of the Secondary Cell is approximately 28 acres
I with an approximate maximum pond elevation of 714 feet. The full pond elevation of Mountain
Island Lake is approximately 646.8 feet.
I The ash basin system was an integral part of the station's wastewater treatment system which
predominantly received inflows from the ash removal system, station yard drain sump, and
stormwater flows. During station operations, inflows to the ash basin were highly variable due
Ito the cyclical nature of station operations. The inflows from the ash removal system and the
station yard drain sump are discharged through sluice lines into the Primary Cell. The
discharge from the Primary Cell to the Secondary Cell is through a concrete discharge tower
Ilocated near the divider dike.
Although the station is retired, wastewater effluent from other non-ash-related station
I discharges to the ash basin is discharged from the Secondary Cell, through a concrete
discharge tower, to Mountain Island Lake. The concrete discharge tower drains through a 30-
inch-diameter corrugated metal pipe into a concrete-lined channel that discharges to Mountain
IIsland Lake. The ash basin pond elevation is controlled by the use of concrete stop logs.
2.3 Permitted NPDES Wastewater and Stormwater Outfalls
I Table 1 provides a list of existing and proposed permitted NPDES wastewater and stormwater
outfalls and descriptions of permitted waste streams mentioned in NCDENR's draft NPDES
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Duke Energy Carolinas,LLC i Plan for Identification of New Discharges 11..)�
Riverbend Steam Station Ash Basin
ISECTION 2-SITE DESCRIPTION
permits. Locations of existing and potential "new" wastewater and stormwater outfalls included
in the draft NPDES permit are shown on Figure 2.
Table 1. NPDES Wastewater and Stormwater Outfalls
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NPDES Outfall
Wastewater Description of
Outfalls Coordinates Waste Stream Description of Effluent
I ' Cooling water consisting of intake screen
35°29'80"N Catawba River backwash and water from the plant chiller
001: 80° 58' 13"W s 1XMountain Island Lake) system, turbine lube oil coolers, condensate
I coolers, main turbine steam condensers and
the intake tunnel dewatering sump.
002 35°22'99"N Catawba River Ash basin discharge consisting of induced
80°57'32"W. (Mountain Island Lake) draft fan and preheater bearing cooling water,
stormwater from roof drains and paving,
treated groundwater,track hopper sump
(groundwater), coal pile runoff, laboratory
Yard sump overflow drain and chemical makeup tanks and drums
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35°21' S1" N rinsate wastes, generalplant/trailer sanitary
002A Catawba River
80° 58' 20"W I Mountain Island Lake) wastewater, turbine and boiler rooms sumps,
vehicle rinse water, and stormwater from pond
areas, upgradient watershed, and
135°21' 54" N miscellaneous stormwater flows.
101
80° 58'01"W
1 102 35°21' 54" N
80°57'57"W
103 35°22'08" N
80°57' 54"W
1 104 35°22' 15" N
80°57'46"W
1 105 35°22' 02" N
80°57'46"W
106 35°22' 01"N
80° 57' 28"W Surface flow towards
1 010 Catawba River
(Mountain Island Lake) Twelve(12)ash basin groundwater seeps.
107 35° 22'01"N
80° 57' 25"W
108 35°21' 54" N
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80°57'22"W
109 35°22' 15" N
80° 57'46"W
1 110 35°22'08" N
80° 57' 36"W
111 35°22'08" N
80° 57'36"W
1 112 35°22'08" N
80°57' 32"W
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Former stormwater Outfall 1. Contains
011 35°29' 80"N Catawba River stormwater and groundwater flow, also
80° 58' 13"W (Mountain Island Lake) includes wastewater from 10,000 gallon oil
separator tank#3.
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Duke Energy Carolinas,LLC I Plan for Identification of New Discharges Fn
Riverbend Steam Station Ash Basin
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SECTION 2-SITE DESCRIPTION
NPDES Outfall
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Stormwater Outfall Description and
Outfalls Coordinates Receiving Water Body Drainage Area Runoff Description
1 24-inch-diameter _
35° 21' 38" N corrugated metal pipe
SW001 g0° 58' 30"W (CMP)to intake canal
Catawba River
(Mountain Island Lake) ma9.area runoff the powerhouse roof,
1 21-inch-diameter CMP to switchyard, and yard are south of the
SW002 35°21' 38" N intake canal powerhouse. Rail lines that transport coal are
80° 58' 30"W Catawba River located within this area and coal residuals are
(Mountain Island Lake) present in the rail bed.
I24-inch-diameter
CMP to
SW003 ll"
35°21'40" N intake canal
80° 58' 32"W Catawba River
(Mountain Island Lake)
15-inch-diameter
35°21'22" N reinforced concrete pipe Drainage area runoff from Horseshoe Bend
SW00480°58'32"W
CatawbaP
PRiver Beach Road.
(Mountain Island Lake)
Drainage area between stormwater outfalls
-18-inch-diameter CMP SW003 and SW006. The 18-inch CMP will be
35° 21'40" removed. Duke Energy will notify DEMLR
SW003A 0° 58' 32"W Catawba River that the potential for stormwater
!I018 , }(Mountain Island Lake) discharges has ceased,and monitoring
requirements will not apply.
' 21' 39"N 36-inch-diameter CMP
SW006 35° Catawba River Drainage area runoff from station yard areas
80° 58' 32"W (Mountain Island Lake) and main oil storage tank area.
' 24-inch-diameter steel Drainage area runoff from the gravel road and
SW007 35°21' 80"N pipe laydown area north of the coal pile storage
0° 58'28"W Catawba River area. The 30-inch ductile iron pipe leading
(Mountain Island Lake) to SW007 and SW007 will be removed.
1 12-inch-diameter ductile Duke Energy will notify DEMLR that the
35°21'80" N iron pipe potential for stormwater discharges has
SW007A 80° 58'28"W leading to Catawba River ceased,and monitoring requirements will
(Mountain Island Lake) not apply.
35°21' 51"N 36-inch-diameter CMP to Drainage area runoff from the cinder storage
SW008 80° 58' 16"W Catawba River area, part of the ash stack planning for
(Mountain Island Lake) removal, and the coal pile area.
35°21' 38" N 18-inch-diameter CMP to
SW010 80°58'41"W Catawba River
(Mountain Island Lake)
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18-inch-diameter CMP to
SW011 35°21'33" N Catawba River Drainage area runoff from the Lark
80°58'45"W (Mountain Island Lake) Maintenance Facility.
35° 21'37" N 8-inch-polyethylene pipe
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SW012 80° 58'42"W Catawba River
(Mountain Island Lake)
The 15-inch CMP leading to SW013 will be
35°21'42"N 15-inch-diameter CMP to removed. Duke Energy will notify DEMLR
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SW013 Catawba River that the potential for stormwater
80° 58' 30"W (Mountain Island Lake) discharges has ceased,and monitoring
requirements will not apply.
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Duke Energy Carolinas,LLC I Plan for Identification of New Discharges En
Riverbend Steam Station Ash Basin
' SECTION 2-SITE DESCRIPTION
NPDES Outfall
' Stormwater Outfall Description and
Outfalls Coordinates Receiving Water Body Drainage Area Runoff Description
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Drainage area runoff surrounding the septic
tank. The 8-inch CMP leading to SW014
35°21'42"N 12-inch-diameter CMP to and/or any other outfalls in this area will be
SW01480° 58' 30"W Catawba River removed. Duke Energy will notify DEMLR
' (Mountain Island Lake) that the potential for stormwater
discharges has ceased,and monitoring
requirements will not apply.
35°21'42" N 12-inch-diameter CMP to Pipes discovered during an engineering field
' SW015
80°58'30"W Catawba River evaluation and designated in this permit as
(Mountain Island Lake) stormwater outfalls SW015. SW016, and
24-inch-diameter CMP to SW017 and discharging to the Catawba River
SW016 35°21'42" N Catawba River (Mountain Island Lake). Upon abandonment
1 80°58'30"W (Mountain Island Lake) or removal of the pipes leading to these
outfalls, Duke Energy will notify DEMLR
35°21'42" N 30-inch-diameter RCP to that the potential for stormwater
SW01780°58' 30"W Catawba River discharges has ceased,and monitoring
(Mountain Island Lake) requirements will not apply.
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Duke Energy Carolinas,LLC I Plan for Identification of New Discharges l_♦Z
Riverbend Steam Station Ash Basin J
SECTION 3-SITE GEOLOGY AND HYDROGEOLOGY
Section 3 - Site Geology and Hydrogeology
3.1 Site Geologic/Soil Framework
1 Riverbend and its associated ash basin system are located in the Charlotte terrane of the
Carolina Zone (Pippin et al. 2008), or as described in the older belt terminology, the Charlotte
Belt of the Piedmont physiographic province (Piedmont) (North Carolina Geological Survey
1985). The Charlotte terrane is characterized by mostly felsic to mafic plutonic rocks which
intrude a suite of mainly metaigneous rocks and minor metasedimentary rocks (Pippin et al.
2008).
' The soils that overlie the bedrock in the area have generally formed from the in-place
weathering of the parent bedrock. The fractured bedrock is overlain by a mantle of
unconsolidated material known as regolith. The regolith, where present, includes the soil zone;
a zone of weathered, decomposed bedrock known as saprolite; and alluvium. Saprolite, the
product of chemical and mechanical weathering of the underlying bedrock, is typically
composed of silt and coarser granular material up to boulder size and may reflect the texture of
the rock from which it was formed. The weathering products of felsic rocks may be sandy-
textured and rich in quartz content while mafic rocks form a more clayey saprolite (LeGrand
1 2004).
3.2 Site Hydrogeologic Framework
Piedmont topography is characterized by gently rounded sloped hills and valleys. Recharge
typically occurs on upland areas and slopes while groundwater discharge is concentrated in
surface water bodies and lowland areas. LeGrand's (1988, 2004) conceptual model of the
groundwater setting in the Piedmont incorporates the above two medium systems into an entity
that is useful for the description of groundwater conditions. That entity is the surface drainage
' basin that contains a perennial stream or river(LeGrand 1988). Each basin is similar to
adjacent basins and the conditions are generally repetitive from basin to basin. Within a basin,
movement of groundwater is generally restricted to the area extending from the drainage divides
1 to a perennial stream or river(Slope-Aquifer System; LeGrand 1988, 2004). Rarely does
groundwater move beneath a perennial stream or river to another more distant stream (LeGrand
2004).
1 Therefore, in most cases in the Piedmont, the groundwater system is a two-medium system
(LeGrand 1988) restricted to the local drainage basin. The groundwater occurs in a system
composed of two interconnected layers: residuum/saprolite and weathered rock overlying
' fractured crystalline rock separated by the transition zone. Typically, the residuum/saprolite is
partly saturated and the water table fluctuates within it. Water movement is generally through
' the fractured bedrock. The near-surface fractured crystalline rocks can form extensive aquifers.
The character of such aquifers results from the combined effects of the rock type, fracture
system, topography, and weathering. Topography exerts an influence on both weathering and
' the opening of fractures while the weathering of the crystalline rock modifies both transmissive
and storage characteristics.
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Duke Energy Carolinas,LLC I Plan for Identification of New Discharges En
Riverbend Steam Station Ash Basin J
SECTION 3-SITE GEOLOGY AND HYDROGEOLOGY
The aquifer system in the Piedmont typically exists in an unconfined or semi-confined condition
in the bedrock zone. Under natural conditions, the general direction of groundwater flow can be
approximated from the surface topography. Groundwater moves both vertically down through
the regolith and parallel to the bedrock surface to areas where groundwater discharges as
' seepage into streams, lakes, or other surface water bodies.
RBSS is located on a peninsula in the Catawba River on the north side of Horseshoe Bend
' Beach Road (Figure 2). This road runs generally west to east and is located along a local
topographic divide. Based on the slope-aquifer system, groundwater at the site is expected to
flow downward from this topographic divide to the ash basins and discharge into Mountain
Island Lake (Catawba River).
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Duke Energy Carolinas,LLC I Plan for Identification of New Discharges ���
Riverbend Steam Station Ash Basin
SECTION 4-IDENTIFICATION OF NEW DISCHARGES
Section 4 - Identification of New Discharges
4.1 Purpose of Inspection
' The purpose of the inspection is to identify new discharges and indicators of potential new
discharges, including toe drain outfalls, seeps, and weeps associated with the coal combustion
residuals surface impoundment (ash basin).
4.2 Seepage
Seepage is considered to be the movement of wastewater from the ash basin through the ash
basin embankment, the embankment foundation, the embankment abutments, through residual
material in areas adjacent to the ash basin, or through the bottom of the ash basin (if the flow
eventually reaches the ground surface). Therefore, a seep is defined in this document as an
expression of seepage at the ground surface above the ordinary high water mark of any waters
of the state. Only seeps that have the presence of a discernible, confined and discrete
conveyance to the surface water will be considered a new seep warranting further evaluation of
' flow and pollutant characterization. A weep is understood to have the same meaning as a seep.
Indicators of seepage include areas where water is observed on the ground surface and/or
where vegetation suggests the presence of seepage. Seepage can emerge anywhere on the
downstream face, beyond the toe, or on the downstream abutments at elevations below normal
pool. Seepage may vary in appearance from a "soft,"wet area to a flowing "spring." Seepage
may show up first as only an area where the vegetation is lusher and darker green than
surrounding vegetation. Cattails, reeds, mosses, and other marsh vegetation often become
established in a seepage area.' However, in many instances, indicators of seeps do not
' necessarily indicate the presence of seeps.
4.3 Area To Be Inspected for New Discharges
1 The areas to be inspected for new discharges and indicators of potential new discharges are the
areas of the site where water contained in the ash basin might infiltrate into the underlying
' residual material and be expressed as seepage. This would include the earthen embankment
which impounds the ash basin and certain adjacent areas.
The extent of the areas to be inspected was determined based on the generalized LeGrand
conceptual model the concept of the slope-aquifer system, and the site topography. In this
generalization, flow of water from the ash basin would be expected to be located within the
slope-aquifer compartment and to be below the full pond elevation of the ash basin. The areas
to be inspected are shown on Figure 2.
4.4 Inspection Procedure
' The inspection procedure for identification of new discharges and indicators of potential new
discharges associated with the Buck ash basin system is provided in Appendix A. In addition to
the specific requirements for the inspection, Appendix A also provides the general requirements,
' Dam Operation, Maintenance, and Inspection Manual, North Carolina Department of Environment and
Natural Resources, Division of Land Resources, Land Quality Division, 1985(Revised 2007).
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Duke Energy Carolinas,LLC I Plan for Identification of New Discharges En
Riverbend Steam Station Ash Basin J
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the frequency of inspections, documentation requirements, and provides a decision flow chart
Ifor determining if the potential new discharge is associated with the ash basin.
Duke Energy will be further classifying seeps into non-engineered seeps at locations where the
I seepage emerges from natural or residual material and engineered seeps (i.e., toe drains).
Appendix B provides the history and current state of seeps identified with regards to official
location and type (non-engineered seeps and engineered seeps).
1 4.5 Stormwater Outfalls
If a stormwater outfall is discharged during periods that do not coincide with precipitation events,
I the water exiting the outfall will be sampled to determine if Coal Combustion Products (CCP) or
other wastes are discharging from the outfall. These areas will be identified, photographed,
sampled, and potentially added to the NPDES wastewater permit.
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Duke Energy Carolinas,LLC I Plan for Identification of New Discharges En
Riverbend Steam Station Ash Basin J
IISECTION 5-REFERENCES
Section 5 - References
' North Carolina Geological Survey, 1985, Geologic map of North Carolina: North Carolina
Geological Survey, General Geologic Map, scale 1:500000.
' LeGrand, H.E. 1988. Region 21, Piedmont and Blue Ridge, p.201-208, in Black, W.,
Rosenhein, J.S., and Seaber, P.R., eds., Hydrogeology: Geological Society of America,
The Geology of North America, v. 0-2, Boulder, Colorado, 524p.
LeGrand, Harry, Sr. 2004. A Master Conceptual Model for Hydrogeological Site
' Characterization in the Piedmont and Mountain Region of North Carolina, North Carolina
Department of Environment and Natural Resources.
Pippin, Charles G., Chapman, Melinda J., Huffman, Brad A., Heller, Matthew J., and Schelgel,
' Melissa E. 2008. Hydrogeologic Setting, Ground-Water Flow, and Ground-Water
Quality at the Langtree Peninsula Research Station, Iredell County, North Carolina,
2000-2005, United States Geological Survey, Prepared in cooperation with the North
' Carolina Department of Environment and Natural Resources, Division of Water Quality.
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CREATED 1993. USGS TOPOGRAPHIC MAP - LAKE NORMAN
SOLTH. CREATED 1993. `- /� '� 5 _ �,. •�
SCALE (FEET) iAli`.'-t'•� �tA
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SITE LOCATION MAP
RIVERBEND STEAM STATION
DUKE ENERGY CAROLINAS, LLC
GASTON COUNTY, NORTH CAROLINA
DATE
APRIL 6. 2015
FIGURE
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, tti
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y , s�r'1 RIVERBEND STEAM
STATION ASH BASIN
` INSPECTION FOR
• 'T' IDENTIFICATION OF
NEW DISCHARGES
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Riverbend Steam Station Ash Basin
IINSPECTION FOR IDENTIFICATION OF NEW DISCHARGES
1. Purpose of Inspection
The purpose of the inspection is to identify new discharges and indicators of potential new discharges,
including toe drain outfalls,seeps,and weeps that arise after the initial submittal of maps required by
I North Carolina General Statute 130A-309.210(a)(2)(ii). Seepage is considered to be the movement of
wastewater from the ash basin through the ash basin embankment,the embankment foundation,the
embankment abutments,through residual material in areas adjacent to the ash basin,or through the
I bottom of the ash basin (if the flow eventually reaches the ground surface.) Therefore,a seep is defined
in this document as an expression of seepage at the ground surface above the ordinary high water mark
of any waters of the state. Only seeps that have the presence of a discernible,confined and discrete
I conveyance to the surface water will be considered a new seep warranting further evaluation of flow
and pollutant characterization. A weep is understood to have the same meaning as a seep. If new
discharges or indicators of potential new discharges are identified,the decision flow chart(see Figure A-
1)will be used to determine if the potential new discharge is from the ash basin and if notification to the
'
North Carolina Department of Environment and Natural Resources(NCDENR) Division of Water
Resources(DWR) is required.
2. General Inspection Requirements
I 2.1. Inspections are to be performed on areas that are below the ash basin full pond elevation and
within the area shown on Figure A-2. The purpose of the inspection is to identify new
discharges and indicators of potential new discharges, including toe drain outfalls,seeps,and
Iweeps associated with the coal combustion residuals surface impoundment(ash basin).
2.2. If required,a larger scale figure showing the locations of outfalls from engineered channels will
I be developed. If a separate figure showing outfalls from engineered channels is not developed,
Figure A-2 will be revised to show these features.
I 2.3. Inspections of areas on or adjacent to the ash basin embankments should be performed within
two months after mowing,if possible.
I 2.4. Inspections should not be performed if the following precipitation amounts have occurred in
the respective time period preceding the planned inspection:
I2.4.1. Precipitation of 0.1 inches or greater within 72 hours or
2.4.2. Precipitation of 0.5 inches or greater within 96 hours
I2.5. Record the most recent ash basin water surface elevation.
2.6. Review previous Inspection for Identification of New Discharge Report(s) prior to performing
Iinspection.
2.7. Review the most recent previous dam inspections.
I
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Riverbend Steam Station Ash Basin
IINSPECTION FOR IDENTIFICATION OF NEW DISCHARGES
2.8. Conduct an interview with the Site Environmental Coordinator prior to performing inspection
Ito inquire about possible changes to site conditions,such as pond elevations,operations,
additions or removal of wastewater discharges to the ash basin, changes to site surface water
drainage, etc.
I
3. Frequency of Inspections
I Inspections will be performed on a semi-annual basis during the following months:April to May and
October to November.
I4. Qualifications
The inspections shall be performed under the direction of a qualified Professional Engineer or
IProfessional Geologist.
5. Documentation of Inspection
IThe inspection shall be documented by the individual performing the inspection. The report should
contain observations and descriptions of the seeps observed,changes in observations compared to
I previous inspections,estimates of flows quantities,and photographs of seeps and outfalls of engineered
channels designed or improved for collecting water from the impoundment. Photographs are to be
numbered and captioned.
IIn addition,the inspection should also include sampling. The facility shall sample for the following
constituents:
I • Chlorides • Selenium
• Fluorine • pH
I • Mercury(method 1631E) • Total Dissolved Solids
• Barium • Antimony
• Iron • Thallium
I • Manganese • Molybdenum
• Zinc • Boron
• Arsenic • Aluminum
I • Cadmium • Sulfate
• Chromium • Total Suspended Solids
I • Coppe •r
• Lead Temperature
• Specific Conductance
• Nickel
IThis sampling is necessary to demonstrate if a discharge/seep contains Coal Combustion Products
(CCPs),if it is some other type of waste stream,or if the seepage is simply not associated with a process
Iwastewater discharge.
1 2

I
Riverbend Steam Station Ash Basin
IINSPECTION FOR IDENTIFICATION OF NEW DISCHARGES
6. Initial Inspection
IAn initial inspection should be performed to identify features and document baseline conditions
including location,extent(i.e.,dimensions of affected area),and flow. Seep locations should be
I recorded using a Global Positioning System (GPS)device. Photographs should be taken from vantage
points that can be replicated during subsequent semi-annual inspections.
I
7. Inspection For New Seeps at Outfalls From Engineered Channels
Inspect the outfalls from engineered channels designed and/or improved (such as through the
I placement of rip-rap)associated with the ash basin dikes to identify new seeps or indicators of new
seeps.
I 7.1. Inspect all outfalls from engineered channels designed and/or improved (such as through the
placement of rip-rap)
I 7.2. Document the condition of the outfall of the engineered channel with photographs.
Photographs are to be taken from similar direction and scale as photographs taken during the
initial inspection.
I7.3. Observe outfall for seepage and for indicators of seeps.
I
7.4. Compare current seepage location,extent,and flow to seepage photographs and descriptions
from previous inspections.
7.5. Record flow rate if measureable.
I
7.6. Sample for the following constituents to demonstrate if a discharge/seep contains CCPs, if it is
some other type of waste stream,or if the seepage is simply not associated with a process
Iwastewater discharge:
• Chlorides • Selenium
I • Fluorine • pH
• Mercury(method 1631E) • Total Dissolved Solids
I
• Barium
•
• Iron • Antimony
• Thallium
• Manganese • Molybdenum
• Zinc • Boron
• Arsenic • Aluminum
• Cadmium • Sulfate
I • Chromium • Total Suspended Solids
• Copper • Temperature
I
• Lead • Specific Conductance
• Nickel
I
3

I
Riverbend Steam Station Ash Basin
IINSPECTION FOR IDENTIFICATION OF NEW DISCHARGES
8. Inspection For New Seeps Not Captured by Engineered Channels
IInspect areas below the ash basin full pond elevation and within the slope-aquifer system shown on
Figure A-2 to identify new seeps or indicators of new seeps. Inspect topographic drainage features that
I potentially could contain new seeps that potentially discharge from the ash basin. Investigations should
include areas where perimeter ditches/swales are located around active or inactive ash basins.
1 8.1. Previously Identified Seeps
a) Inspect previously identified seep locations. Document the condition of the seeps with a
I photograph. Photographs are to be taken from similar direction and at a similar scale as the
photograph documenting original photograph of seep. Describe the approximate
dimensions and flow conditions of the seep. This information may help to demonstrate
Ichanging site conditions over time.
b) If flow measurement device is installed at the outfall, record flow.
Ic) Observe seep to determine if changes to location,extent,or flows are present. Document
changes to location,extent,and/or flow amount or pattern.
Id) Sample for the following constituents to demonstrate if a discharge/seep contains CCPs,if it
is some other type of waste stream,or if the seepage is simply not associated with a process
Iwastewater discharge:
• Chlorides • Selenium
I • Fluorine • pH
• Mercury(method 1631E) • Total Dissolved Solids
• Barium • Antimony
I • Iron • Thallium
• Manganese • Molybdenum
• Zinc • Boron
I • Arsenic • Aluminum
• Cadmium • Sulfate
I • Chromium • Total Suspended Solids
• Copper • Temperature
• Lead • Specific Conductance
I • Nickel
I8.2. New Seep or Indicators of Seep
a) Mark the location of new seep or indicators of seep using a GPS device.
Ib) Document the condition of the seeps or indicators of seeps with a photograph.
1 4

I
Riverbend Steam Station Ash Basin
I
INSPECTION FOR IDENTIFICATION OF NEW DISCHARGES
Describe the approximate dimensions and flow conditions of the seep.
Ic)
d) Sample for the following constituents to demonstrate if a discharge/seep contains CCPs,if it
is some other type of waste stream,or if the seepage is simply not associated with a process
Iwastewater discharge:
• Chlorides • Selenium
I • Fluorine • pH
• Mercury(method 1631E) • Total Dissolved Solids
• Barium • Antimony
I • Iron • Thallium
• Manganese • Molybdenum
I • Zinc • Boron
• Arsenic • Aluminum
• Cadmium • Sulfate
I • Chromium • Total Suspended Solids
• Copper • Temperature
• Lead • Specific Conductance
I • Nickel
Ie) Map the location of new seep or indicator of seep using GPS coordinate points collected
during the site visit.
If) If seep or indicator of seep was not caused by changes in surface water drainage and if the
location is below the ash basin pond elevation,utilize the decision flow chart to determine if
Ithe seep represents a discharge from the ash basin and if notification to DWR is required.
9. Update Maps Identifying Seeps
I If new seeps are identified during the inspection, Figure A-2 shall be updated to show the location of the
new seeps. All seeps located below the ash basin full pond elevation and within the slope-aquifer
system shown are to be shown on Figure A-2.
I
10. Decision Flow Chart
I The decision flow chart developed to determine whether a new seep discharges from the ash basin is
found on Figure A-1.
Iii. Procedure for Notifying NCDENR DWR if New Discharge Is Confirmed
Duke Energy will notify the DWR Regional Office by mail within 5 days after the discovery of a new seep
unless a different timeframe is established and specified in reissued permits. If the new seep represents
I 5

I
Riverbend Steam Station Ash Basin
IINSPECTION FOR IDENTIFICATION OF NEW DISCHARGES
a significant change in flow or pollutant loading from the facility, or a bypass or upset, it may fall under
Iprovisions that would require immediate reporting.
I
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1
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1 6

1
Riverbend Steam Station Ash Basin
INSPECTION FOR IDENTIFICATION OF NEW DISCHI
i
ReN
Is r
bou
1
Does n
could
' Collect water qualit
• Field parame
• Constituent an
1 Compare analytical results from
determined analytical re
1
' Do:
Ind'
Prepare report documenting ins
and based on above evalua
Notes:
1 1. If no new seeps are identified,
2. If new seeps are identified thaSh basin,a single report
will be submitted to NCDENR C
I

6
AREAS OF WETNESS

MN - - M M OM MN r MN M N - - - MI M i MN E
Table B-1 -Riverbend Steam Station Ash Basin—Seep Locations and Descriptions
Area of Location Coordinates Flow Seep Type
Wetness Description (Engineered or Description
Latitude LongitudeNon-Engineered)
S-1 35.365 -80.967 Continuous Located west of the Primary Cell and north of the Cinder Storage Area. Seepage at multiple
locations near the toe of the Primary Cell and Cinder Storage Area dikes and collect in the
general area of S-1. The flow is generally overland with no well defined channel.
S-2 35.365 -80.966 Continuous Located west of the Primary Cell dike at the end of rip-rap lined channel,near the toe of the
Primary Cell dike.The channel collects seepage from the toe of the dike and flows through a
defined channel approximately 1 to 2-ft wide.
S-3 35.369 -80.965 Continuous Located west of the Secondary Cell in a drainage feature downgradient from the toe of the
Secondary Cell dike.Seepage is upgradient of the S-3 device.
S-4 35.371 -80.963 Continuous Located north of the Secondary Cell downgradient of the toe of the northern Secondary Cell
abutment. Seepage flows from channels sampled via S-5 and S-9.
S-5 35.370 -80.963 Continuous Located north of the Secondary Cell along the toe slope of the northern Secondary Cell
abutment.Seepage flows from multiple locations upgradient of the S-5 device.
S-6 35.367 -80.958 Continuous Located east and downgradient of the ash basin,flowing in the general direction of
groundwater flow from the ash basin.
S-7 35.367 -80.957 Continuous Located east and downgradient of the ash basin,flowing in the general direction of
groundwater flow from the ash basin.
S-8 35.365 -80.956 Continuous Located east of the ash basin and Secondary Cell dike.
S-9 35.371 -80.963 Continuous Located north of the Secondary Cell northern abutment at the end of rip-rap lined channel,
near the toe of the abutment.The channel collects seepage from the toe of the abutment and
flows through a defined channel approximately 2-ft wide.
S-10 35.369 -80.960 Intermittent Located east of the Secondary Cell dike downstream of a rip-rap lined channel at the toe of
the dike.The channel collects seepage from the toe of the dike and may(intermittently)flow
through a defined channel approximately 2 to 3-ft wide.Flow was not exhibited at the time
of sampling.
S-11 35.369 -80.960 Continuous Located east of the Secondary Cell dike downstream of a rip-rap lined channel at the toe of
the dike. The channel collects seepage from the toe of the dike and flows through a defined
channel approximately 2 to 3-ft wide.
S-12 35.368 -80.959 Continuous Located at the end of a concrete channel downstream of the toe of the Secondary Cell dike.
Seepage flows from multiple locations along the ground surface downgradient of the toe of
the dike and flows overland.
Notes:
1. Flow description for each sample location is based on multiple site visits performed by HDR Engineering,Inc.(HDR)from November 2013 until April 2014.
2. S-10 did not exhibit flow at the time of sampling.
3. Flow measurements and analytical samples were collected(except for S-10)on April 29,2014.
4. Location coordinates for sampling locations were recorded by HDR using a handheld Trimble GPS unit and are approximate.